Each ARG is an arithmetic expression to be evaluated. Evaluation
is done in fixed-width integers with no check for overflow, though
division by 0 is trapped and flagged as an error. The following
list of operators is grouped into levels of equal-precedence operators.
The levels are listed in order of decreasing precedence.
[tab]id++, id--
[tab]variable post-increment, post-decrement
[tab]++id, --id
[tab]variable pre-increment, pre-decrement
[tab]-, +
[tab][tab]unary minus, plus
[tab]!, ~
[tab][tab]logical and bitwise negation
[tab]**
[tab][tab]exponentiation
[tab]*, /, %
[tab][tab]multiplication, division, remainder
[tab]+, -
[tab][tab]addition, subtraction
[tab]<<, >>
[tab][tab]left and right bitwise shifts
[tab]<=, >=, <, >
[tab]comparison
[tab]==, !=
[tab][tab]equality, inequality
[tab]&
[tab][tab]bitwise AND
[tab]^
[tab][tab]bitwise XOR
[tab]|
[tab][tab]bitwise OR
[tab]&&
[tab][tab]logical AND
[tab]||
[tab][tab]logical OR
[tab]expr ? expr : expr
[tab][tab][tab]conditional operator
[tab]=, *=, /=, %=,
[tab]+=, -=, <<=, >>=,
[tab]&=, ^=, |=
[tab]assignment
Shell variables are allowed as operands. The name of the variable
is replaced by its value (coerced to a fixed-width integer) within
an expression. The variable need not have its integer attribute
turned on to be used in an expression.
Operators are evaluated in order of precedence. Sub-expressions in
parentheses are evaluated first and may override the precedence
rules above.
If the last ARG evaluates to 0, let returns 1; 0 is returned
otherwise.
